1. Field of the Invention
The invention relates to the suspension of a distributing appliance, having an elongated spray-pipe, from the chassis of an agricultural vehicle, of the type set forth in claim 1.
2. Description of the Prior Art
In the spraying of liquid or solid substances over the ground, e.g. for fertilizing, the greater the length of the spray-pipe projecting from both sides of the agricultural vehicle, at right angles to the direction of travel and close to the ground, the more rapid the spraying operation. There is, however, a limit to the length of such spray-pipes in that, in order to ensure uniform distribution of the substances sprayed, the entire length of the pipe must pass over the ground at a distance as uniform as possible therefrom. Since no completely flat track is available to a vehicle operating in a field, it is impossible to prevent the said vehicle from tilting at right angles to its direction of travel, and if the spray-pipe is secured rigidly to the vehicle, at a low height above the ground, the outer ends thereof are likely to strike the ground, even at small angles of tilt.
For this reason, swinging suspensions for distributing appliances have been known for some considerable time (e.g. German Pat. No. 1 181 485). Although these may be used in the case of continuous ruts on one side of the vehicle with otherwise horizontal ground, unevenly undulating ground, causing alternate lateral tilting of the vehicle, results in dangerous swinging of the distributing appliance in its vertical longitudinal plane. Although such distributing appliances can be improved quite easily by means which displace their centres of gravity laterally (German Pat. No. 20 33 773), making it possible to use them on a vehicle travelling along a slope, here again there is a tendency for the pipe to swing, and this swinging is damped only inadequately by resilient damping means (DD Pat. No. 91 743 and German AS No. 26 56 279) because of the restoring forces which counteract the required deflections.
In order to avoid said aforementioned swinging motions of the distributing appliance when travelling along a slope of a hill, it is known by the German AS No. 1 607 387 (Maass) to turn the distributing appliance, itself suspended like a pendulum at an upper longitudinal axis of the agricultural vehicle, around its suspension axis and to fix it relative to the vehicle at the actual angle of the slope, so as to obtain a uniform distance between the distributing appliance and the ground. However, this proposal was never prosecuted, as it is troublesome and practically impossible to compensate in time the inevitable permanent alterations of the angle of the slope of a hill and the uneveness of the track while operating on said slope.
By the FR - A - 2,289,116 (Demaret) are known suspensions of a distributing appliance according to the preamble of claim 1 by means of two cables, articulated rods, or the like tension elements of equal length extending obliquely downward in a bifilar manner from the two ends of a cross beam or the like vehicle chassis, thus providing for a non-circular moving and swinging path of the distributing appliance relative to the travelling agriculture vehicle and therewith providing for a better damping effect than is possible with circular oscillations. Thus suspended, the distributing appliance with a vehicle travelling along a slope, can also be better guided parallel with the ground. However, the disadvantage still remains that, when the vehicle tilts, righting moments are applied to the distributing appliance as a result of gravity and the inertia of the tension elements which, in their turn, tend furtheron to oscillations like a pendulum, and this again leads to undesirable swinging of the said distributing appliance from its horizontal attitude. Furthermore, this swinging suspension of the distributing appliance by tension elements also fails to prevent the said appliance, in the event of a permanent tilt of the chassis, from being deflected, as the tilt increases, through an increasing angle, with the result that the material is again not sprayed sufficiently uniformly.